This invention is generally directed to toner and developer compositions, and more specifically the present invention is directed to processes for eliminating, or minimizing toner deposition, or toner sticking to, for example, electrophotographic, especially xerographic, components like wires, such as those illustrated in U.S. Pat. No. 4,868,600, the disclosure of which is totally incorporated herein by reference. In one embodiment, the process comprises utilizing toner compositions with conductive oxides, especially metal oxides, like tin oxide and titanium oxide. A specific embodiment of the present invention comprises adding a toner comprised of resin particles, pigment particles, a charge enhancing additive, and effective surface additives, such as conductive metal oxides, to a donor roll from a toner supply source, transporting the toner to a development nip situated between an imaging member and the donor roll, and wherein there are present wires, usually two, self spaced above the donor roll, application of an AC field to the wires thereby generating a toner cloud, and development of latent images present on the imaging member by the attraction of toner particles to said image and whereby the undesirable dynamic sticking of toner particles to the wires is avoided or minimized. The aforementioned sticking can cause the development of the images to fail through the formation of large agglomerates of toner particles. These in turn can cause imperfections and vacancies in the toner cloud leading to insufficient development on the image bearing member. This shows up as undesirable streaks on the final developed copies.
The process of the present invention is particularly useful for the scavengeless development apparatus illustrated in U.S. Pat. No. 4,868,600, the disclosure of which is totally incorporated herein by reference. Toner and controlled toner powder cloud are mentioned in this patent. Also, the process of the present invention can in embodiments be selected for the scavengeless development apparatus as illustrated in U.S. Pat. No. 5,032,872, issued Jul. 16, 1991, and U.S. Ser. No. 396,153 , the disclosures of which are totally incorporated herein by reference.
In a patentability search report, the following U.S. Pat. Nos. are listed: 4,868,600, discussed herein; 4,837,100, which discloses a positively charged developer with toner particles containing fine particles of hydrophobic alumina and fine particles of, for example, tin oxide or titanium dioxide, reference the Abstract; apparently the developer "hardly" undergoes toner cloud or toner dropping during development, and this developer produces a high quality image, see column 1 for example; 4,873,185, which discloses a toner which is capable of eliminating tailing, see column 2; the toner contains a certain metal complex compound, and a metal complex salt-type monazo dye having a hydrophilic group; 4,871,616, discloses a surface treated poly methyl silsesquioxane powder characterized by surface treatment with an agent comprising a compound which has at least two radicals attached to a metal atom, or a silicon atom, see the Abstract for example; examples of metal atoms in the surface treating agent include titanium, and tin, see columns 3 and 4; 4,933,251, which discloses a developer with a toner containing, for example, a layer of external additives of fine metal oxides, fine silica particles, and cleaning aid particles, see the Abstract; also see columns 1 and 2, wherein in column 2 it is indicated that there is a greatly decreased tendency for the toner to become attached to nonimage areas; 4,973,540, which discloses a toner with an inorganic fine particle with at least both a negatively and positively chargeable polar group on the surface of the inorganic fine particles, see the Abstract; examples of inorganic fine particles include titanium dioxide, see column 3; and 3,888,678, which discloses treating the surface of toners with a charge control agent; the above patentability search report indicates that the agent used to treat the surface of the particles is comprised of metal oxides, such as titanium dioxide, or tin oxide; however, this teaching cannot be located in the '678 patent.
Toner and developer compositions containing charge enhancing additives, especially additives which impart a positive charge to the toner resin, are well known. Thus, for example, there is described in U.S. Pat. No. 3,893,935 the use of certain quaternary ammonium salts as charge control agents for electrostatic toner compositions. There are also described in U.S. Pat. No. 2,986,521 reversal developer compositions comprised of toner resin particles coated with finely divided colloidal silica. According to the disclosure of this patent, the development of images on negatively charged surfaces is accomplished by applying a developer composition having a positively charged triboelectric relationship with respect to the colloidal silica. Further, there are illustrated in U.S. Pat. No. 4,338,390, the disclosure of which is totally incorporated herein by reference, developer and toner compositions having incorporated therein as charge enhancing additives organic sulfate and sulfonate compositions; and in U.S. Pat. No. 4,298,672, the disclosure of which is totally incorporated herein by reference, positively charged toner compositions containing resin particles and pigment particles, and as a charge enhancing additive alkyl pyridinium compounds, inclusive of cetyl pyridinium chloride.
Other prior art disclosing positively charged toner compositions with charge enhancing additives include U.S. Pat. Nos. 3,944,493; 4,007,293; 4,079,014 and 4,394,430.